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Yes, I am near the area, so all those stations are heard all over the LW MW and HF throughout when the active antennas and longwire is used.
I thought maybe the filters are only the option, or moving QTH. The former would be easier, quicker and cheaper option but would it work well effectively? I was not so sure. 
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Filters will only work if the unwanted signals are being generated inside your receivers. For the reasons I have already given I think that unlikely.
If something outside your receiver is generating an unwanted signal on the 4 to 5MHz band then no amount if filtering will remove it. How could it? Filters only remove signals out of band, and the signals you want are in that same 4 to 5MHz band, along with the spurious signals.
The only cure is either to remove the non-linear element doing the mixing to produce spurious signals in the 4 to 5MHz band, or to move QTH. And a "non-linear" element might not be your antenna amplifier - it could be something as weird as a rusty fence or rusty bolt in a gutter. And those might not be near your house!
And sorry I have worse news horror you. I don't know what the harmonic levels are from those MW transmitters, but a quick check on ITU standards, suggest broadcasters can get away with 50mW maximum. Those MW transmitters I listed will have harmonics falling into your tropical broadcast band. Depending on exactly how far you are away from the broadcast transmitters, 50mW fed into what is probably a rather large broadcasting antenna could well be putting a substantial signal out over several miles. Again filtering at your receiver will do absolutely nothing to help in this situation.
Richard